It is highly creditable to the ingenuity of our ancestors that the
peculiar property of fermented liquids, in virtue of which they "make
glad the heart of man," seems to have been known in the remotest periods
of which we have any record. All savages take to alcoholic fluids as
if they were to the manner born. Our Vedic forefathers intoxicated
themselves with the juice of the "soma"; Noah, by a not unnatural
reaction against a superfluity of water, appears to have taken the
earliest practicable opportunity of qualifying that which he was obliged
to drink; and the ghosts of the ancient Egyptians were solaced by
pictures of banquets in which the wine-cup passes round, graven on
the walls of their tombs. A knowledge of the process of fermentation,
therefore, was in all probability possessed by the prehistoric
populations of the globe; and it must have become a matter of great
interest even to primaeval wine-bibbers to study the methods by which
fermented liquids could be surely manufactured. No doubt it was soon
discovered that the most certain, as well as the most expeditious, way
of making a sweet juice ferment was to add to it a little of the scum,
or lees, of another fermenting juice. And it can hardly be questioned
that this singular excitation of fermentation in one fluid, by a sort
of infection, or inoculation, of a little ferment taken from some other
fluid, together with the strange swelling, foaming, and hissing of the
fermented substance, must have always attracted attention from the more
thoughtful. Nevertheless, the commencement of the scientific analysis of
the Sphenomena dates from a period not earlier than the first half of the
seventeenth century. At this time, Van Helmont made a first step, by
pointing out that the peculiar hissing and bubbling of a fermented
liquid is due, not to the evolution of common air (which he, as the
inventor of the term "gas," calls "gas ventosum"), but to that of a
peculiar kind of air such as is occasionally met with in caves, mines,
and wells, and which he calls "gas sylvestre."
But a century elapsed before the nature of this "gas sylvestre," or as
it was afterwards called, "fixed air," was clearly determined, and it
was found to be identical with that deadly "choke-damp" by which the
lives of those who descend into old wells, or mines, or brewers' vats,
are sometimes suddenly ended; and with the poisonous aeriform fluid
which is produced by the combustion of charcoal, and now goes by the
name of carbonic acid gas.
During the same time it gradually became evident that the presence of
sugar was essential to the production of alcohol and the evolution of
carbonic acid gas, which are the two great and conspicuous
products of fermentation. And finally, in 1787, the Italian chemist,
Fabroni, made the capital discovery that the yeast ferment, the
presence of which is necessary to fermentation, is what he termed a
"vegeto-animal" substance; that is, a body which gives off ammoniacal
salts when it is burned, and is, in other ways, similar to the gluten of
plants and the albumen and casein of animals.